The present invention relates generally to a Doppler-based traffic radar system and, more particularly to such a system and related method for determining the speed of a target without detection by an operator of the target or subsequent targets utilizing a traffic radar detector.
Law enforcement officers have utilized Doppler-based traffic radar systems to monitor vehicle speeds and enforce traffic speed limit laws for many years. Throughout this period of time, numerous improvements in both the underlying technology and in the specific application of new processing techniques for the traffic radar systems themselves, have afforded law enforcement officers greater flexibility and improved reliability in carrying out their duties. One such improvement evident in most traffic radar systems presently being marketed includes the capability to more accurately and reliably monitor the speed of certain vehicles while the patrol vehicle is either in a stationary or a moving mode of operation. In fact, the recent traffic radar systems can now successfully monitor the speed of vehicles approaching the moving patrol vehicle in an opposite lane.
In addition to these capabilities, such radar systems also provide the law enforcement officer the capability to monitor a group of target vehicles simultaneously and to determine the fastest vehicle within the group and/or the vehicle presenting the traditional strongest reflected return signal. Each of these new or improved existing capabilities provide the law enforcement officer with a more complete picture of the traffic environment and thus, a more flexible and reliable basis for making more informed decisions.
Despite all the improvements in both the underlying technology utilized in these traffic radar systems and the radar systems themselves, drivers who elect to drive at a speed above the legal speed limit are still able to significantly reduce the possibility that their illegal activity will be detected by a traffic radar-system by purchasing one of several commercially available traffic radar detectors. Typical traffic radar detectors are known in the art including those manufactured by such companies as Uniden America Corporation and Cobra Electronics Corporation, among others. These radar detectors are similarly technically advanced and have enjoyed tremendous commercial success as evidenced by the number of sales made to the public.
In an attempt to limit the effectiveness of these radar detectors, most traffic radar systems are capable of operation in both a continuous transmit mode and an intermittent transmit mode. In the intermittent transmit mode, the operator manually triggers the radar system dependent upon several conditions including for example, the number of approaching vehicles or perhaps an initial visual determination of the speed of a single approaching vehicle.
While this intermittent mode of operating traffic radar systems has limited the ability of commercial radar detectors to detect their presence in some scenarios, many scenarios remain in which the radar detectors remain effective. For example, intermittent operation of radar systems in monitored zones having heavy traffic patterns or continuous light traffic patterns may trigger alert signals from a radar detector which are sufficient to allow an alert and cautious driver in and/or approaching the monitored zone to discern the presence and operation of the radar system, thus avoiding detection.
Thus, while traffic radar systems are capable of a high degree of accuracy with regard to vehicle speed measurements, they are subject to detection by commercial radar detectors and thus vehicle operators who elect to speed are often able to avoid detection. Accordingly, a need is clearly identified for a traffic radar system and related methods of operating such systems which are capable of determining the actual speed of a target vehicle while substantially eliminating the possibility of detection by an operator of the target utilizing a radar detector system.
Necessarily, such a radar system and related methods would substantially eliminate the ability of vehicle operators to rely on radar detectors in furtherance of their illegal activities. Accordingly, such a system would significantly increase their risk of being detected while reducing the benefit of owning a radar detector to a point where the number of individuals willing to accept the risks associated with driving at a rate of speed above the legal speed limit is significantly reduced.
In accordance with the purposes and objectives of the present invention, a novel and improved Doppler-based traffic radar system is provided that is adapted to control the period of time or to limit the duration of an initial transmission of microwave energy or radar signal from the radar system toward a moving target. By limiting the duration of the initial transmission period, presently available commercial radar detectors are substantially unable to detect and/or elect not to report the presence of the radar signal. Accordingly, the traffic radar system is capable of determining the speed of a target while substantially eliminating the possibility of detection by an operator of the target utilizing a traffic radar detector.
In order to limit the duration of the initial transmission period, the radar system of the present invention monitors the amount of the microwave energy or radar signal portion reflected from the moving target. Upon receiving a sufficient amount of the reflected return signal to determine the speed of the target, the radar system ends the initial transmission. Alternatively, the radar system may simply end the initial transmission following a limited period of time.
Once the reflected return signal is obtained, the radar system calculates and displays the speed of the moving target. Dependent upon the speed of the target, the radar system operator has the ability to discontinue the monitoring of the speed of the target or to reinitiate the transmission of microwave energy or radar signal for subsequently calculating the speed of the target and tracking the speed both visually and aurally for a period of time sufficient to support a citation.
In accordance with an important aspect of the present invention, the traffic radar system may be operated from a stationary or a moving platform. During operation from a moving platform, the radar system determines the speed of the platform for calculating the speed of the moving target utilizing a portion of the return signal reflected from a stationary object in a manner well known in the art. Alternatively, a second antenna transmitting the radar signal away from the target may be used to determine the speed of the target.
The following description shows and describes a preferred embodiment of this invention simply by way of illustration of one of the modes best suited to carry out the invention. As it will be realized, the invention is capable of other different embodiments, and its several details are capable of modifications in various, obvious aspects all without departing from the invention. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive.